Optical disks, magnetic disks and magneto-optical disks are increasingly popular mediums for digitally storing information. Such disks are typically enclosed in a box shaped disk cartridge having apertures through which a laser light source can read (or write to) the disk contained within the cartridge.
In certain large-scale disk cartridge storage and retrieval systems, disk cartridges are stored in one or more racks in an array of storage slots. Commonly, the slots are oriented horizontally and are arranged in a vertical column such that the disk cartridges sit horizontally one on top of another in the individual slots. Storage and retrieval systems may have one or more of such columns of disk cartridge storage slots. This type of system includes a cartridge retrieval mechanism which is movable into position adjacent a slot. The mechanism includes apparatus for grasping a cartridge from the slot, drawing it out from the slot, holding the cartridge in a sleeve, transporting it to a different location, such as a recording/reading/erasing station, and ejecting the cartridge.
Accordingly, the mechanism includes a gripper assembly for grasping and releasing cartridges, a cartridge sleeve assembly for temporarily storing the grasped cartridge, and a carriage assembly for moving the gripper and sleeve assemblies into position adjacent a selected slot so that the gripper can retrieve the disk cartridge and place it in the sleeve. The entire carriage is then moved to another location where the disk cartridge can be ejected from the sleeve assembly into a recording, reproducing, and/or erasing station. In a small disk storage and retrieval system comprising only a single column of slots, the carriage assembly may need to be moveable only in one direction, e.g., vertically. However, in a larger system comprising an array of rows and columns of slots, the carriage assembly would need to be movable in at least two dimensions (horizontally and vertically). In fact, depending on the particular design of the system, the carriage assembly may need to be moveable in all three dimensions (i.e., have three degrees of freedom).
A sleeve assembly commonly comprises a cartridge receiving sleeve which is open at one end and sized to accept a disk cartridge. Within the sleeve is a moveable gripper assembly which can be advanced forward to extend from the sleeve opening into a position where a disk cartridge can be grasped. The gripper assembly is then moved back into the sleeve, pulling the cartridge from its slot into the sleeve.
In order to provide for movement of the gripper for drawing disk cartridges into and ejecting disk cartridges from the sleeve, a gripper drive motor with associated gears and belts is mounted directly on the sleeve assembly. Further, in certain systems, the sleeve assembly itself must be rotatable so the cartridge contained within the sleeve assembly can be rotated. For instance, in certain systems it may be necessary to flip cartridges 180.degree. so that information can be read from or written to either face of the disk contained within the cartridge. In such systems, the sleeve assembly is pivotally mounted on the carriage and the carriage includes a second motor with associated gears and belts for rotating the sleeve assembly relative to the carriage.
The carriage itself is slidably mounted on a vertical shaft and a vertical worm screw. The shaft keeps the carriage in the proper position with respect to the horizontal plane while the worm screw is driven by a third motor to cause the carriage to move vertically along the shaft. If the carrier must be able to move horizontally also, the support shaft and worm screw may themselves be mounted on an additional carriage which is horizontally movable. This second carriage may be similar in design to the first carriage described above except that it would be supported on a horizontal, rather than vertical, support shaft and worm screw.
During assembly of such carriages, the various motors must be precisely mounted relative to the belt drive gears so as to provide the proper tension on the belts. This typically has been done by loosely mounting the motor in its support member with the belt engaged between the motor and the remote gear or gears and coupling the motor to a force measuring device. The motor is then moved until the force measuring device shows the proper tension on the belt, at which point the screws are tightened to permanently fix the motor in position. This method has proved to be labor intensive and also to require frequent adjustment in the field.
Another frequently encountered problem in these types of carriages relates to the fact that, if the shaft and the worm screw are not exactly parallel, significant stresses can be applied to the carriage, shaft, and/or screw leading to premature wear and failure.
Another common problem with these types of carriages is that, after a period of use, components may fatigue or otherwise be bent so that parts may not align properly. Thus, when the various carriages and components are moved and rotated so as to place the aperture of the sleeve assembly in front of a particular slot, the aperture actually may not be precisely aligned with the slot. This may lead to premature failure of the system.
Accordingly, it is an object of the present invention to provide an improved carriage mechanism for a disk storage and retrieval apparatus.
It is a further object of the present invention to provide a self tensioning motor mount for a carriage system of a disk storage and retrieval apparatus.
It is yet another object of the present invention to provide a flexible mounting apparatus for coupling a carriage mechanism to a worm screw to allow for relative planar movement between the carriage and the worm screw with minimal relative rotational movement.
It is a further object of the present invention to provide a carriage for a sleeve assembly having superior positional stability.